Spinneret and its method of production



Dec. 30, 1952 J. D. Mcc. MACKAY EIAL $623,241

SPINNERET AND ITS METHOD OF PRODUCTION Filed Sept. 8, 1950 F162 FIG 5FIG-4 INVENTORS: John Doug/as McClure Mucky}; A rf/rur We/Ieslv StewartC/ ark BYM W V mORNEYS Patented Dec. 30, 1952 UNITED STATES PATENTOFFICE SPINNERET AND ITS METHOD OF PRODUCTION Application September 8,1950, Serial No. 183,712

In Great Britain October 31, 1949 9 Claims.

The present invention is concerned with spinnerets and a method fortheir production.

The conventional method of spinneret manufacture has been that ofpunching or drilling holes of the required diameter in thin sheets ofmetallic material requiring precision instruments and takingconsiderable time.

The object of the present invention is to provide improved plasticspinnerets and a method for their production which will enable suchspinnerets to be produced conveniently and cheaply.

According to the present invention a method for the production ofplastic spinnerets comprises forming a laminated structure comprisinglayers of substantially parallel filaments which can be removed bychemical treatment held separated by material unaffected by saidchemical treatment, the said parallel filaments of one layer beingsubstantially parallel to the said parallel filaments of any otherlayer, forming a solid block of plastic of the kind which is notdissolved by said chemical treatment in and throughout and surroundingsaid laminated structure, cutting said block into plates substantiallyperpendicular to the said filaments which can be removed by saidchemical treatment, and removing the short filaments left in said platesby said chemical treatment.

The said layers in said laminated structure can be formed from wovenfabric having substantially parallel filaments which can be removed bychemical treatment which does not remove the filaments crossing saidparallel filaments.

The substantially parallel filaments can be for example metallic wiresof the requisite diameter and solubility in acids and the filamentscrossing said parallel filaments are not soluble in these acids.

The filaments crossing said parallel filaments may consist for exampleof textile filaments, glass filaments or metal wires unattackable by theacid which dissolves said parallel filaments.

If desired the said layers in said laminated structure may be formedfrom textile covered filaments or plastic covered filaments.

Again, if desired, each of said layers in the laminated structure may beseparated by at least one layer of permeable material which is notattackable by said chemical treatment, as for example fabric material.

If plastic spinnerets according to the invention contain unattackablefibres which are distributed in the plastic and therethrough at least inthe a 2 vicinity of the perforations, spinnerets of high mechanicalstrength are formed.

Preferably in said woven fabric thesubstantially parallel filamentswhich can be removed by a chemical treatment are metallic wires of therequisite diameter and solubility in acid while the filaments crossingsaid parallel filaments are not soluble in said acids and may consist oftextile filaments, glass filaments or metal wire unattachable by theacid used for dissolving said parallel filaments.

The removal by said chemical treatment includes removal by solution ina, suitable solvent, removal by chemical reaction and electrolyticremoval.

Preferably the said permeable material consists of fabric material.

Examples of a plastic of the kind which is not dissolved by saidchemical treatment are those derived from liquids convertible into aplastic as for instance liquid polymerisable compounds for example,monomers such as methyl methacrylate and styrene; or thermosettingcompositions comprising compounds capable of forming crosslinking resinsand a solution of a catalyst therefor in a polymerising solvent as forinstance a liquid composition comprising di-methacrylic ester ofbis(beta hydroxy ethyl) phthalate, benzoyl peroxide and n-butylmethacrylate.

In accordance with one embodiment of the invention the said laminatedstructure can be formed by winding the said woven fabric into a spiralinterleaved if desired with a spiral strip of said fabric material, soas to produce a roll of cloth with all the soluble filaments parallel tothe axis.

In accordance with another embodiment of the present invention the saidlaminated structure is formed by superimposing rectangular layers ofsaid woven fabric, so that the parallel filaments of one layer areparallel to the said parallel filaments of any other layer, andseparating said layers if desired by rectangular layers of said fabricmaterial.

By the term laminated structure" is included a structure in which thelayers thereof can be plane surfaces, curved surfaces or surfaces formedby rolling a strip of material as for in stance into a cylindrical body.

The laminated structure" may have for instance a circular or rectangularcross-section.

The said solid block of plastic is formed by treating the said wovenlayers of fabric and the permeable material by impregnation eitherbefore the formation of the said laminated structure or after the saidlaminated structure has been produced with subsequent polymerisation.

In accordance with still another embodiment of the invention the saidlaminated structure can be formed as a rigid bundle. preferably ofsubstantially circular cross-section. of textile of plastic coveredmetal wires lying substantially parallel to one another. The said bundlecan be formed for example from a continuous length of covered metal wirewound spirally on a collapsable swift so that the bundle of wires formedinto a ring thereon has a transverse semi-circular cross-section. Thering of wires thus formed after removal from the swift can be deformedinto a bundle of substantially parallel wires and of circularcross-section. The bundle can be suitable wound at each end to keep thewires of the bundle tightly together.

The method of the present invention is illustrated by way of example byreference to the diagrammatic drawings accompanying the specificationwhereof Figures 1, 2 and 4 illustrate the first embodiment of theinvention and Figures 1, 3 and 4 illustrate the second embodiment of theinvention.

Fig. 1 is a perspective view of semi-wire cloth with a warp of 0.0044"diameter iron wires spaced at 100 wires to the inch and with a weft offine cotton threads, Fig. 2 is a perspective view of a length of thesemi-wire cloth of Fig. 1 rolled into a cylinder, Fig. 3 is aperspective view of a cylinder formed from rectangular layers of thesemi-wire cloth of Fig. 1 said layers being separated one from the otherby rectangular layers of fabric material, and Fig. 4 is a perspectiveview in part section of a solid cylindrical block of plastic showing acut plate from which the wires have been removed and the remaining blockin which the wires are still present.

In accordance with the first embodiment of the invention and withreference to Figs. 1, 2 and 4 the semi-wire cloth I with iron wires 2and cotton threads 3 is cut into strips about 2 in. wide and 22 in. longwith the iron wires 2 running across and the cotton wires 3 runningalong them. Two of these strips I are rolled up with separating strips 2in. wide of calico 4 and further layers of calico 4 are added to producea plain margin 5. The rolling is done in a dish containing a liquidresin such as a composition comprising dimethacrylic ester of bis(betahydroxy ethyl) phthalate, benzoyl peroxide and n-butyl methacrylatewhich will polymerise when heated. Care is taken to see that the wholeof the roll is thoroughly impregnated. The roll 6 thus produced isplaced in a tight fitting rubber bag with a further small quantity of aliquid resin and the bag closed. The whole is to be in a vessel heatedat a temperature of 45 C. rising after 2 days to 110 C. Then the vesselis cooled. The resulting block 1 is cut on a lathe into slices 8 abouta; in. thick by 1% in. diameter, the part containing the iron wires 2occupying about 1 in. diameter. These slices 8 are polished and thewires 2 are dissolved out by immersing in warm dilute hydrochloric acidcontaining a trace of cupric chloride.

An alternative method of impregnation is to put the dried roll 8 into atight fitting rubber tube closed at the bottom with a valve and to applya vacuum to the top end. The valve is then opened to a supply of liquidresin which is then drawn right through the roll 6. This method has theadvantage of removing all the air from the cloth before the resin isapplied.

4 An alternative way for instance of removing the iron wire 2 from theslice 8 is to put the slice 8 between mercury on one side and a saltsolution on the other side and to connect the two liquids to a source ofelectricity in such manner that the iron wires form the anode.

In accordance with the second embodiment of the invention the semi-wirecloth I is cut into a number of rectangular strips of different widths,the maximum width being 1 /2 in. and all of equal length of say 2 /2 in.Rectangles of fabric material are also produced of similarly gradedwidth with a maximum width of 2 in. The length of all these rectanglesof fabric material is also 2 in. A laminated structure is produced fromthese rectangles of wire cloth and fabric material by interposing alayer of fabric material between layers of the wire cloth. The laminatedstructure is produced in the form of a compact cylinder by arranging therectangles of wire cloth and fabric material in such a manner that thewidest rectangles are in the middle and that there is a gradation in thewidth of the rectangles as these rectangles are superimposed one uponthe other.

The laminated structure thus produced can be impregnated with the liquidresin in accordance with any of the methods employed in the firstembodiment and the solid block of plastic eventually produced is alsocut into thin plates substantially perpendicular to the iron wires 2 andthese wires are then removed from the thin plates by a chemicaltreatment.

The laminated structure which can be produced in accordance with thethird described embodiment of the invention for instance a bundle ofsubstantially parallel cotton covered iron wires can also be impregnatedwith the liquid resin in accordance with any of the methods employed inthe first embodiment and the solid block of plastic eventually producedis also cut into thin plates substantially perpendicular to the cottoncovered iron wires and the iron wires therefrom are then removed fromthe thin plates by a chemical treatment.

What we claim is:

l. A method for the production of plastic spinnerets which comprisesforming a laminated structure composed of a plurality of substantiallyparallel metal wires which are dissolvable by chemical treatment, saidwires being held in parallel spaced relationship from each other byfabric material and said laminated structure being impregnated with aliquid composition which is convertible into a solid resin that isunaffected. by said chemical treatment, thereafter converting saidliquid composition into solid resin form to produce a solid block ofresin in, throughout and surrounding said laminated structure, cuttingsaid block into plates substantially perpendicular to said metal wires,and thereafter removing the short wires left in said plates by saidchemical treatment.

2. The method of claim 1, wherein said laminated structure is formed oflayers of woven fabric made up of substantially parallel metal wireswhich are dissolvable by the chemical treatment and filaments crossingsaid parallel metal wires which are not removable by said chemicaltreatment.

3. The method of claim 2, wherein each of said layers of woven fabric isseparated by a layer of permeable fabric material which is notattackable by said chemical treatment.

. 4. The method of claim 1, wherein said structure is formed bysuperimposing rectangular layers of woven fabric made up ofsubstantially parallel metal wires which are dissolvable by the chemicaltreatment and filaments crossing said parallel metal wires which are notremovable by said chemical treatment.

5. Th method of claim 1, wherein said laminated structure is formed bywinding a woven fabric made up of substantially parallel metal wireswhich are dissolvable by the chemical treatment and filaments crossingsaid parallel metal wires which are not removable by said chemicaltreatment into a roll in which the metal wires extend parallel to theaxis.

6. A method for the production of plastic spinnerets which comprisesforming a rigid bundle of substantially parallel, covered metal wires,said wires being dissolvable by chemical treatment but the coveringsthereof being unaffected by said chemical treatment and said laminatedstructure being impregnated with a liquid composition which isconvertible into a solid resin that is also unaffected by said chemicaltreatment, thereafter converting said liquid composition into solidresin form to produce a solid block of resin in, throughout andsurrounding said laminated structure, cutting said block into platessubstantially perpendicular to said metal wires, and thereafter removingthe short wires left in said plates by said chemical treatment.

7. The method of claim 1, wherein the liquid 6 composition is athermosetting composition comprising compounds capable of formingcrosslinking resins and a solution of a catalyst therefor in apolymerizing solvent.

8. The method of claim '7 wherein the thermosetting composition is aliquid composition comprising dimethacrylic ester ofbis(beta-hydroxyethyl) phthalate benzoyl peroxide and n-butylmethacrylate.

9. Plastic spinnerets characterised in that the plastic thereof hasfibres distributed therethrough at least in the vicinity of theperforations.

JOHN D. McC. MACKAY. ARTHUR W. S. CLARK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,654,936 Jones Jan. 3, 19282,266,349 Wempe Dec. 16, 1941 2,360,479 Detrick, Oct. 1'7, 19442,506,244 Stopka May 2, 1950 2,510,598 Oles June 6, 1950 FOREIGN PATENTSNumber Country Date 161 526 Great Britain Mar. 23. 1922

